By Kim Eun-jung SEOUL, Jan. 6 (Yonhap) -- The ruling Grand National Party's efforts to revamp its old-fashioned, corrupt image ahead of this year's key elections are in danger of fizzling out, as the party has been hit by yet another bribery scandal allegedly involving its top leaders.

Rep. Ko Sung-doug earlier this week alleged that an aide to one of then-candidates for chairperson gave him an envelope stuffed with 3 million won (US$2,600) before a party leadership vote. The lawyer-turned-lawmaker, first elected in April 2008, said he immediately returned the money but the candidate later became the GNP's new leader.

There have been three GNP leadership votes since 2008 and Ko did not specify which he was referring to.

The GNP was quick to request prosecutors launch an investigation into the bribery allegation, wary of negative public feeling from mushrooming speculation about its internal corruption.

Officials of the Grand National Party file documents with the prosecution on Jan. 6 after the party requested an investigation into the allegations regarding its money-ridden leadership vote. (Yonhap)

There have been previous rumors some candidates tried to bribe fellow members to win party contests, but this is the first time a GNP lawmaker has raised specific allegations.

Rep. Cho Jun-hyuk, who contested the 2010 leadership election, said the national convention has been affected by nepotism and money, and criticized political practices often plagued by mudslinging and factional conflicts.

"I have heard of (candidates) customarily giving money to representatives of local branches. I was aware of a couple of cases, although I haven't checked them all," Cho said in a radio interview.

Though Ko did not name a specific person, National Assembly Speaker Park Hee-tae, who won a closely contested race in 2008, was named in the local media as a potential suspect. Park denied any connection with the bribery allegations.

Parliamentary Speaker Park Hee-tae is questioned by reporters whether he delievered money to fellow lawmakers during a party leadership campaign in 2008. (Yonhap)

The GNP's interim leader, Park Geun-hye, called for a prompt investigation to leave no suspicions in regards to the party's leadership vote.

The party's leading presidential contender took the helm of the party's emergency council last month with a pledge to enact sweeping reforms ahead of the April votes, after ex-chairman Hong Joon-pyo stepped down under pressure from reformist lawmakers.

Watchers are now questioning whether Park's leadership can revive the scandal-ridden party, which has fallen to a new low, as she did in the 2004 election campaign.

Ahead of the 2004 general elections, several GNP lawmakers were arrested for taking massive campaign donations from the nation's largest conglomerates in return for favors during the 2002 presidential election campaign. The widespread illegal donations revealed by prosecutors shocked the nations, as big businesses groups, including LG, Hyundai, SK and Samsung, were discovered to have delivered massive cash gifts to politicians.

Park, who was serving as chairwoman at the time, made tearful appeals to people to vote for her party, playing a key role in reviving the then-hopeless GNP, and was later dubbed the "queen of elections."

As public anger grew, party spokesman Hwang Young-chul on Friday made a public apology, saying the party will soon announce further measures in regard to the allegations.

Ko said he will fully cooperate with the prosecution's investigation, saying he made the revelation to bring change to such corrupt political practices.

As prosecutors are set to summon witnesses and party members to verify Ko's allegations, party members worry that scenes of politicians being summoned will further tarnish their image, negating efforts to claim back voters in the upcoming elections.

Political parties are making do-or-die efforts to boost their chances in the April polls, seen as a crucial test for public sentiment before people vote to elect a new president in December.

Opposition parties have ratcheted up attacks against the ruling party, which has been stained by a series of scandals involving its lawmakers.

"The ruling party's comprehensive structure of corruption has been unveiled," the Democratic Unity Party's floor leader Kim Jing-pyo said at a party meeting. "The GNP is rotten to the core."

Adding to the woes is a widening prosecution investigation that has seen an aide to a GNP lawmaker arrested on charges of masterminding a hacking attack on the Web site of the national election watchdog on the day of the October by-elections.

Students urge prosecutors to thoroughly investigate a cyber hacking allegedly masterminded by an aide to a GNP lawmaker on the day of the October by-elections. (Yonhap)

Rep. Choi Ku-sik denied any involvement in the scheme, but left the party last week after growing pressure from his own party. The party's emergency council has launched a civilian committee to verify whether the ongoing prosecution investigation is fair and transparent in order to dispel lingering suspicions that higher ranks in the GNP may have been involved in the hacking.